1. Field of the Invention
The present invention relates to a hybrid vehicle provided with an engine that can run in a cylinder cut-off state where intake and exhaust valve lifts are both made zero, and a motor/generator that functions as both a motor and a generator.
2. Description of the Related Art
In a conventional hybrid vehicle, the motor/generator functions as a generator when the engine is in a fuel cut state during deceleration so as to carry out regenerative braking, thereby recovering the kinetic energy of the vehicle as electrical energy. In Japanese Patent Application Laid-open No. 2001-140665, when a hybrid vehicle is being decelerated the engine is run in a cylinder cut-off state by making the intake and exhaust valve lifts zero, thus minimizing the pumping loss so as to make the engine braking ineffective, and thereby enhancing the energy recovery efficiency of the regenerative braking.
Legislation makes it obligatory to detect and display abnormalities in each part of an engine mounted in a vehicle (OBD; on board diagnosis), and a negative intake pressure sensor and an Exhaust Gas Recirculation (“EGR”) control valve are targets for the detection of abnormalities based on the engine negative intake pressure. However, as in the engine described in Japanese Patent Application Laid-open No. 2001-140665 above, if the engine is run in a cylinder cut-off state where the intake and exhaust valve lifts are made zero during deceleration, because the engine does not exhibit a pumping action, no negative intake pressure is generated, and there is the problem that abnormalities in the negative intake pressure sensor and the EGR control valve cannot be detected.